Chris,
Here is one source link I found using a quick search for your
Carter YF throttle plate screws.
The page also shows the vendor offering a tap to use in cleaning up the threads in your throttle shaft if that is needed.
Your picture looks like the original screws were brass and yes, they probably got sucked into the engine, although they could be just resting in one of the intake runners??? No idea (without completely unbuttoning your engine) to know if they may have gotten stuck someplace "bad" and have or could cause damage.
They are however small enough that they could have been ingested and blown out without doing any damage too. If you're not hearing anything out of the ordinary, you may be fine.
Hope this helps.
Dan
